CH640135A5 - Abrasive having a high fluoride compatibility for toothpaste - Google Patents

Description

This invention relates to abrasives with high fluoride tolerance for dentifrices suitable for use in therapeutic toothpaste formulations containing both soluble fluorides and enamel solubility reducing agents and soluble phosphates as penetrants in the plaque film. The invention further relates to a method of making these abrasives and to toothpastes containing the abrasives, including toothpastes that both reduce enamel solubility, i.e. Fluorides, as well as penetrants contained in the plaque film. Such toothpastes have a high fluoride tolerance as well as a high cleaning effect.

The task of an abrasive in formulations intended for use in the oral cavity is to remove various deposits, including the plaque film, from the tooth surface. It is known that the plaque film adheres firmly to the teeth and often contains brown or yellow pigments, which gives the teeth an unsightly appearance. An advantageous toothpaste abrasive should achieve maximum removal of the plaque without excessive wear of the hard tooth tissue. Dental researchers are therefore constantly developing toothpaste abrasives that allow teeth to be cleaned satisfactorily and yet do not undesirably wear and damage the oral tissues.

In addition to the abrasives, the well-known therapeutic toothpastes contain sources of fluoride ions. The favorable reduction in the occurrence of dental caries due to the topical application of fluoride ion-containing solutions to the enamel surface is well known. In particular, it is assumed that the fluoride ions react with the tooth enamel with a pH value between approximately 4 and 8, whereby the acid solubility of the tooth enamel is reduced. The tooth enamel treated with fluoride is more resistant to the formation of dental caries. Therefore, therapeutic toothpaste formulations are formulated in such a way that the solutions formed when brushing the teeth release fluoride ions.

It has been postulated that the effectiveness of the fluoride treatment to achieve a favorable solubility-inhibiting and anti-cariogenic effect depends on the amount of fluoride ions available for absorption by the tooth enamel to be treated. For this reason it is of course desirable to formulate toothpastes in such a way that the solutions formed during tooth brushing provide a maximum amount of fluoride ions. However, attempts to utilize such anti-cariogenic agents containing ionic fluoride in toothpastes suitable for normal home use have been unable to give the theoretical maximum amount of soluble fluoride because ionic fluoride tends to be inactivated and thereby inactive the enamel becoming inaccessible. This means that toothpastes lose their ability to deliver the theoretical maximum amount of soluble fluoride when stored (at speeds that increase with temperature). For the present purposes, the means

Soluble fluoride content of any given toothpaste is the ppm concentration of fluoride ions present in the supernatant liquid after centrifuging a toothpaste slurry (toothpaste: water weight ratio = 1: 3).

Fluoride ion sources tend to react with toothpaste contaminants and with toothpaste components such as abrasives, buffers, etc. Such reactions reduce the ability of the fluoride ion source to release "soluble fluoride" when used. The tendency of the toothpastes described here to retain their soluble fluoride content after storage is referred to in this patent as “tooth-pasta fluoride compatibility”. The toothpaste fluoride compatibility of a particular toothpaste thus corresponds to that percentage of the theoretical maximum amount of fluoride ion source that after storage for a certain time and at a certain temperature, e.g. during a week at approx. 50 ° C. is actually measured as soluble fluoride. Similarly, the inclination of such a toothpaste component, e.g. an abrasive to react with the fluoride ion source and thereby reduce the measured content of "soluble fluoride" compared to the theoretical maximum amount of fluoride ion source (especially in the presence of penetrants in the plaque film of the type described in detail below) as "abrasive fluoride compatibility »Expressed. The test procedures used in this patent to determine toothpaste fluoride compatibility values and abrasive fluoride compatibility values are described below.

One of the toothpaste components that can cause particular difficulties when formulating fluoride toothpastes is an abrasive component made of precipitated silicon dioxide. Precipitated silica abrasives are, however, desirable for toothpastes because they have desirable low dentin wear levels. Certain of the known precipitated silica abrasives are generally compatible with sources of soluble fluoride, but do not have a high enough abrasive effect to ensure effective cleaning of the teeth. Certain other known precipitated silica abrasives have acceptable cleaning performance but poor abrasive fluoride compatibility as determined by the method mentioned below. It is believed that none of the known, precipitated silica abrasives have both high abrasive fluoride compatibility and an acceptable cleaning effect (evident from the usual "radioactive dentin abrasion" values). There is therefore a clear need for the formulation of precipitated silicon dioxide abrasives which not only have high abrasive fluoride compatibility, but also have an acceptable cleaning performance. The aim of the present invention is therefore to develop precipitated silicon dioxide abrasives which have a high abrasive fluoride compatibility and at the same time have an acceptable cleaning performance.

Another dentifrice component that can have a particularly unfavorable effect on the content of soluble fluoride in certain toothpastes is soluble phosphate. When using toothpastes, soluble phosphates serve to increase the penetration ability of the fluoride ions into the plaque film. For this reason, the addition of soluble phosphates to fluoride toothpastes is desirable. It has been shown, however, that penetrants consisting of soluble phosphates in the dental plaque film, in particular in combination with silicon dioxide abrasives, tend to favor the loss of soluble fluoride in toothpastes containing such materials, which is why such toothpastes have low toothpaste fluoride compatibility values. It

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there is therefore a clear need for the formulation of precipitated silica abrasives that have high toothpaste-fluoride compatibility when used in fluoride-containing toothpastes that contain soluble phosphates as penetrants in the plaque film.

There is also a need to develop fluoride toothpastes that can contain precipitated silica abrasives in combination with soluble phosphates. Accordingly. One of the aims of the present invention is the development of fluoride toothpastes, the soluble phosphates and | precipitated silicon dioxide abrasives and, despite this fact, have relatively high levels of soluble fluoride even after prolonged storage.

It has now surprisingly been found that the abovementioned objectives can be achieved by the abrasive according to the invention. Using the present abrasives, fluoride toothpastes (especially those containing soluble phosphates) can be produced, which show a high toothpaste fluoride compatibility and excellent cleaning effect.

Therapeutic toothpastes are naturally known which contain calcium phosphate materials as abrasives, but these calcium materials are present in large quantities, as mentioned above. Such toothpastes are e.g. in U.S. Patent Nos. 3,624,199 issued November 30, 1971 to Norfleet et al, and 3,864,471 issued February 4, 1975 to Mills et al. Toothpastes are also known which contain small amounts of alkaline earth metal ions, e.g. Calcium ions. Such toothpastes are illustrated, for example, in U.S. Patent No. 3,991,177, issued November 9, 1976 to Vidra et al. This patent describes toothpastes containing a stabilizer activator for a dextranase enzyme agent, said stabilizer activator consisting of a salt, e.g. Calcium chloride, in an amount of 0.001 to 0.3 wt .-%. These toothpastes can also contain therapeutic fluoride and the abrasive is calcium carbonate.

Other toothpastes containing alkaline earth metal compounds or ions are disclosed in U.S. Patent 3,095,356, issued June 25, 1963 to Moss, 3,122,483, issued February 25, 1964 to Rosenthal, 3,669,221, issued June 13, 1972 Hase, 3 782 446, issued January 1, 1974 to Walter, 3 842 168,

issued October 15, 1974 to Colodney, and 3,689,537 issued September 5, 1972 to Kuder. However, none of these previously published patents discloses therapeutic toothpastes which contain a precipitated silica with low water retention capacity (“low structure”) as abrasive, which contains about 10 to 300 ppm of alkaline earth metal ions, as described here. In U.S. Patent No. 3,893,840, the term "structure" is defined as the ability of silicon dioxide or silicates to retain water in the form of a wet cake. With high water retention, e.g. 70 to 85%, one speaks of «high structure», with a low water retention, i.e. less than 70%, preferably 50 to 70%, one speaks of “low structure”.

The present invention therefore relates to a new toothpaste abrasive which is characterized in that it contains a precipitated, amorphous silicon dioxide which contains 10 to 300 parts of alkaline earth metal ions per million parts of amorphous silicon dioxide and which furthermore has a radioactive dentin abrasion value of at least 40, a packing density of 0.24 to 0.55 g / ml, an oil absorption of 70 to 95 ml / 100 g, a BET surface area of 100 to 250 mVg, a percentage loss on ignition of 4 to 6% and fluoride compatibility values of at least 90 % when incorporated into toothpastes containing fluoride. The oil absorption value was determined according to ASTM method D-281, the linseed oil being replaced by mineral oil with a Saybolt viscosity of 340 to 350. The abrasive usually has an average particle size of 5 to 15 / im.

The process according to the invention for producing the abrasive defined above is characterized in that an alkali metal silicate with a molar ratio of SÌO2 to X2O of 2.0 to 2.7, in which X is an alkali metal, is dissolved in water and the solution at a reaction temperature in the range acidified from 77 to 91 ° C with a mineral acid until the precipitation of the silica is substantially complete, thereafter the mineral acid addition continues until the pH is 6.0 or less, then the material obtained at a temperature around 10 to 30 ° C higher than the reaction temperature, digested for 10 to 30 minutes, the slurry thus obtained filtered and the solid product washed with fresh water, the resulting wet filter cake reslurried in water with stirring and so much alkaline earth metal ions in the form of a sufficient amount soluble alkaline earth metal salt adds that the moist filter cake alkaline earth metal ions in an amount of n contains 10 to 300 parts per million parts based on the dry, recoverable product in the slurry, the resulting mixture is stirred to ensure that the effective amount of alkaline earth metal ions adhere to the surface of the silica, and finally the solid product dries and wins.

The present invention further relates to a toothpaste which

(A) 6 to 35% by weight of a precipitated silicon dioxide abrasive as defined above,

(B) 0.01 to 3.0% by weight of a water-soluble, fluoride-containing material which forms fluoride ions in aqueous solution,

(C) 3 to 55% by weight of a humectant,

(D) 0.2 to 2.0% by weight of a binder and

(E) contains 15 to 80% by weight of water and, when slurried with water in a weight ratio of 3 parts by weight of water to 1 part by weight of toothpaste, has a pH of 4 to 8.

The precipitated, amorphous silica contains 10 to 300 parts, preferably 10 to 100 parts, of alkaline earth metal ions, preferably calcium ions, per million parts of amorphous silicon dioxide. The precipitated, amorphous silicon dioxide has a radioactive dentin abrasion value (RDA value) of at least 40, preferably from approximately 70 to 120, a percentage loss on ignition (hereinafter referred to as “LOI”) in the range from 4 to 6%, a packing density in the range from 0.24 to 0.55 g / ml, an oil absorption in the range from 70 to 95 ml / 100 g and a BET surface area in the range from 100 to 250 m2 / g and preferably an average particle size in the range from 5 to 15 fim. If the dental abrasives discussed here are incorporated into toothpastes, they have a high fluoride tolerance of at least 90% and result in excellent cleaning performance.

The abrasives of this invention are precipitated, amorphous silicas which can be obtained by general methods such as those described in U.S. Patent Nos. 3,893,840 issued to Wason on July 8, 1975 and No. 3,988,162 issued to Wason on October 26, 1976, and in U.S. Patent Application Ser. No. 703,496, filed July 8, 1976, and which have been subsequently treated with alkaline earth metal ions in the manner described above.

The abrasives according to the invention differ from the precipitated silicon dioxide preparations which, according to the information in the US patent application Ser. No. 723,345 of September 15, 1976 and their continuation in part application No. 826 901 of August 24, 1977 have been treated with alkaline earth metal ions. According to the US patent application Ser. No. 826 901 Silicas treated with alkaline earth metals are abrasives that are suitable for incorporation in toothpastes

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are suitable to prevent corrosion of unlined aluminum toothpaste tubes. These corrosion-preventing, precipitated silicas, as described in the US patent application Ser. No. 826 901 are described, silicon dioxide, which are produced by a so-called sulfate lye method. In this method an electrolyte, e.g. an alkali metal sulfate, mixed with the alkali metal silicate liquor during acidification with mineral acid, for example as described in US Pat. Nos. 3,960,586 and 3,928,541. The products according to US patent application No. 826 901 can be referred to as precipitated silicas which are intimately mixed with alkaline earth metal ions, the amount of alkaline earth metal ions being in the range of the amount used according to the invention. However, the abrasives according to the invention have different properties than the silicon dioxides which are produced by the sulfate lye method. When used in certain fluorine-containing toothpastes, the silicon dioxide materials obtainable by means of the sulfate lye method do not give the increased fluoride compatibility values of the abrasives according to the invention. The better fluoride compatibility values of the dental abrasives according to the invention can only be achieved with the help of silicon oxides, which are produced by the so-called fresh water alkali metal silicate process as described above.

In this process, no electrolytes are used in the production of the untreated, precipitated silicas, e.g. Sodium sulfate. It was also found that the alkaline earth metal ions which are intimately associated with the silicon dioxide obtained must be present in the abrasives according to the invention in the narrow range specified above in order to ensure the fluoride compatibility required for the purposes according to the invention. The abrasives according to the invention thus have fluoride compatibility values of at least 90%, while the abrasives according to the US patent application Ser. No. 826 901 generally have compatibility values of 89% or less, determined according to the compatibility tests described in the present patent.

It is assumed that the improved fluoride compatibility of the dental abrasives according to the invention can be attributed to the way in which the silanol groups present are bound to the surface of the silicon dioxide product. It is assumed that the silanol groups in the case of the silicas according to the invention, which are made from fresh water silicate, are more easily accessible on the surface of the material than in the case of silicas, which are made from sulphate liquor silicate according to the US patent application Ser. No. 826 901 of August 24, 1977. Furthermore, the surface acidity of the fresh water silicas due to the silanol groups is higher than the corresponding acidity of the silicas which are produced by the sulfate lye process. Since the silanol groups in these two materials are different, the surface acidity of the sulfate lye process products does not respond well to the calcium treatment for fluoride compatibility. The products according to US patent application No. 826 901 also have higher grinding values than the silicon dioxide according to the invention. Thus, the present abrasives must be of the type described in Ser. No. 826 901 described, treated with alkaline earth metal silicas.

The alkali metal silicate used in the process according to the invention is preferably a sodium silicate. The solution prepared therefrom preferably has a sodium silicate concentration in the range from approximately 10 to 17% by weight, preferably from 12.5 to 15.5% by weight, the best results being obtained with a sodium silicate of the composition Na20-2 , 6 SÌO2 achieved. The mineral acid used in the process according to the invention preferably has a concentration of approximately 10 to 20

% By weight. The mineral acid used is preferably sulfuric acid, with which the best results are achieved. However, as can be seen in the prior art (Vergi, for example, U.S. Patent Nos. 3,988,162, 3,893,840 and U.S. Patent Application Ser. No. 703,496 dated July 8, 1976), other acids can be used , e.g. Use nitric acid, phosphoric acid, hydrochloric acid, carbonic acid, etc.

In the preferred embodiment, only a portion of the alkali metal silicate solution is charged to the reactor and then heated with stirring, whereupon the sulfuric acid and the remainder of the alkali metal silicate solution are simultaneously added to the original silicate solution at the reaction temperature. Preferably initially about 8 to 12% by weight of the silicate solution is introduced into the reactor. The rest is then added with the 15 sulfuric acid. The time during which the alkali metal silicate and sulfuric acid are added to the alkali metal silicate in the reactor can be determined in advance and generally depends on the volume of the reactor and the difficulties in controlling the temperature and stirring. After the addition of the alkali metal silicate solution is complete, the mineral acid is added continuously until the pH of the reaction slurry has dropped below 6.0, preferably to about 4.6 to 5.0. The slurry thus obtained consists of the precipitated silicon dioxide contained in the reaction medium.

After a pH of less than 6.0 is reached, the slurry is heated to a temperature which is 10 to 30 ° C higher than the original reaction temperature during a digestion time. The pH 30 can be adjusted again if necessary. The resulting slurry is then filtered and the residue washed with fresh water to remove any by-products, such as sodium sulfate, that may be present in the silica product. The moisture content in the filter cake obtained is generally in the range from about 60 to 66%, with a material having a low water retention capacity being obtained. The above reaction up to this point is generally the same as the reactions in known U.S. Patent Nos. 3,893,840 and 3,988,162 and in U.S. Patent Application No. 703,496 in the manufacture of silica from fresh water alkali metal silicate.

In the method according to the invention, after filtering and washing the moist filter cake consisting of silicon dioxide, the material is subjected to a treatment with earth-45 alkali metal ions in order to produce the new abrasives according to the invention. According to the invention, the moist, washed filter cake (e.g. at ambient temperature with stirring) is reslurried in its own water or with additional fresh water. While stirring, the slurry is then treated with a sufficient amount of alkaline earth metal ions, preferably calcium ions, in the form of a salt with sufficient solubility to provide 10 to 300 ppm or 0.001 to 0.03% by weight (based on the weight of the dry, recoverable silica) Earth-55 alkali metal ions intimately associated with the silica.

The alkaline earth metal ions added at this point in time are preferably calcium ions because they are easily accessible and inexpensive and, moreover, are easy to incorporate into the silicon dioxide. The calcium ions can be incorporated into the silica in any sufficiently water-soluble form (i.e. with a solubility of at least 0.07 g / 100 ml H2O at 20 ° C). For example, calcium nitrate, calcium oxide, calcium hydroxide or calcium chloride solutions can be used. Lime or calcium hydroxide is preferred. However, solutions of organic salts, e.g. Use calcium acetate or calcium formate solutions and the like. The corresponding

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Strontium and magnesium salts can also be used. Salts with the purity required for food should be used.

After treatment with the alkaline earth metal ions, the slurry of the filter cake is stirred, preferably vigorously for 10 to 20 minutes, particularly 15 minutes, to ensure that the effective amount of alkaline earth metal ions adhere to the surface of the silica. The solid product thus obtained is then dried and recovered. Drying is preferably carried out in a spray dryer at an inlet temperature of 483 ° C and an outlet temperature of 122 ° C, as is known per se. The material can then be ground to the desired degree of fineness.

The toothpastes according to the invention, which contain the abrasives according to the invention, have a satisfactory tooth cleaning performance and moreover have excellent abrasive fluoride compatibility properties. The toothpastes according to the invention contain 6 to 35%, preferably 10 to 20% by weight, of the precipitated silicon dioxide abrasives according to the invention.

The therapeutic toothpastes according to the invention further contain 0.01 to 3% by weight, preferably 0.1 to 1.0% by weight, of a water-soluble, fluorine-containing material which provides fluoride ions in aqueous solutions. These fluoride ions combine with the tooth enamel and thereby reduce the solubility of the tooth enamel in acid. The application of fluoride ions to tooth enamel serves to protect the teeth against decay.

A wide variety of types of fluoride ion-providing materials can be used in the agents according to the invention as a source of soluble fluorides. Examples of suitable fluoride-providing materials can be found in U.S. Patent No. 3,535,421 to Briner et al, issued October 20, 1970 and U.S. Patent No. 3,678,154 to Widder et al, issued July 8 1972. Preferred fluoride ion sources that can be used are sodium fluoride (NaF), stannofluoride (SnF2), potassium fluoride (KF), a mixture of potassium fluoride and stannofluoride (SnFî-KF), indium fluoride (InFî), zinc fluoride (ZnF2), Ammonium fluoride (NH4F) and stannochlorofluoride (SnClF). Sodium fluoride and stannofluoride and mixtures thereof are particularly preferred.

The toothpastes according to the invention preferably supply approximately 50 to 500 ppm, in particular approximately 100 to 400 ppm, fluoride ions in the aqueous solutions with which the tooth surfaces come into contact when the toothpastes according to the invention are used in the mouth. As will be described in more detail below, these solutions are mimicked by making a slurry of the toothpastes according to the invention in water in a weight ratio of 1: 3 and then centrifuging to obtain an aqueous supernatant liquid. The fluoride ion concentration in such a liquid is considered to be a measure of the "soluble fluoride" emitted by a given fluoride toothpaste.

A binder is used in an amount of 0.2 to 2.0% by weight to prevent separation of the liquid from the solid phase of the toothpaste. Such binders are well known to the toothpaste specialist. The best known binders are the seaweed colloids, e.g. Carragheen (Irish moss or the branded product Viscarin) and derivatives of cellulose, e.g. Sodium carboxymethyl cellulose or hydroxyethyl cellulose. Another type of binder suitable for this purpose consists of rubbers, e.g. 1) Vegetable gums, e.g. Guar gums, and 2) fermentation products, e.g. Xanthan gum. Since the natural and synthetic aqueous dispersions of such binders are attacked by microbes or mold, it can be caused by

It may be advantageous to add a relatively small amount of a preservative to the toothpastes according to the invention. Examples of typical preservatives for this purpose are the esters of p-hydroxybenzoic acid.

Toothpaste binders are described in detail in U.S. Patent No. 2,839,448 to Hager et al, issued June 17, 1958 and U.S. Patent No. 3,862,307 to DiGiulio, issued January 21, 1975.

Another necessary component of the toothpastes according to the invention are the humectants. Suitable humectants are also well known to the toothpaste specialist. Such humectants serve to retain moisture and thereby prevent toothpastes from hardening in the air. Certain humectants can also give toothpastes a desired sweetness or taste. The humectants generally make up 3 to 55% by weight, preferably 20 to 36% by weight, based on the toothpaste.

Suitable humectants for the purposes according to the invention are edible polyhydric alcohols, such as e.g. Glycerin, sorbitol, xylitol and propylene glycol. Sorbitol is often used as a 70% aqueous solution as it is known under the brand name Sorbo. Mixtures of glycerin and sorbitol are particularly preferred as a humectant component for the toothpastes according to the invention.

Water is another essential element of the toothpastes according to the invention. The water used in the manufacture of commercial toothpastes should be deionized and contain no organic contaminants. The water content is 15 to 80% by weight, preferably 15 to 40% by weight, based on the toothpastes according to the invention.

In addition to the necessary components mentioned above, the toothpastes according to the invention can contain various other optional conventional toothpaste components. These optional ingredients include (1) foaming agents, (2) plaque film penetrants, (3) flavor-correcting or flavor-enhancing agents and sweeteners, (4) anti-tartar and anti-plaque agents, and (5) pigments and colorants.

(1) Foaming agent

A preferred optional ingredient is a foaming agent. Suitable foaming agents are those which are sufficiently stable and form foam within a wide pH range, i.e. anionic, nonionic, cationic, zwitterionic and amphoteric organic synthetic detergents. Foaming agents of these types are described in greater detail in U.S. Patent No. 3,959,458 to Agricola et al, issued May 25, 1976 and U.S. Patent No. 3,937,807 to Haefele, issued February 10, 1976.

Anion-active foaming agents suitable for the purposes of the invention are the water-soluble salts of alkyl sulfuric acids with 8 to 18 carbon atoms in the alkyl radical and the water-soluble salts of sulfonated monoglycerides of fatty acids with 10 to 18 carbon atoms. Sodium lauryl sulfate and sodium coconut monoglyceride sulfonates are examples of anionic surfactants of this type. Mixtures of anionic surfactants can also be used.

The nonionic foaming agents which can be used in the toothpastes according to the invention can generally be defined as compounds which are obtained by condensation of alkylene oxides (hydrophilic in nature) with an organic hydrophobic compound which can be aliphatic or alkylaromatic in nature. Examples of suitable nonionic foaming agents of this type are the "Pluronics", polyethylene condensates of alkylphenols, products by condensation

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of ethylene oxide with the reaction product of propylene oxide and ethylenediamine, ethylene oxide condensates of aliphatic alcohols, long-chain tertiary amine oxides, long-chain tertiary phosphine oxides, long-chain dialkylsulfoxy-de and mixtures of such materials.

The zwitterionic synthetic foaming agents which are suitable for the toothpastes according to the invention can generally be referred to as derivatives of aliphatic quaternary ammonium, phosphonium and sulfonium compounds, in which the aliphatic radicals can be unbranched or branched and in which one of the aliphatic substituents has 8 to 18 carbon atoms and an anionic, water-solubilizing group, e.g. Contains carboxylate, sulfonate, sulfate, phosphate or phosphonate.

The cationic foaming agents suitable for the toothpastes according to the invention can generally be referred to as quaternary ammonium compounds with a long alkyl chain which contains 8 to 18 carbon atoms, e.g. Lauryltrimethylammonium chloride, cetylpyridinium chloride, cetyltrimethylammonium bromide, diisobutylphenoxyethoxy-ethyldimethylbenzylammonium chloride, coconut alkyltrimethylammonium nitrite, cetylpyridinium fluoride etc., are particularly preferred as the quaternary ammonium fluoride, n. In this patent these quaternary ammonium fluorides are described as detergents. The cationic foaming agents can also have a germicidal effect in certain toothpastes of the type claimed here.

The amphoteric foaming agents which can be used for the present invention can generally be described as derivatives of aliphatic secondary and tertiary amines, in which the aliphatic radical can be unbranched or branched and in which one of the aliphatic substituents has 8 to 18 carbon atoms and one has an anionic, water-solubilizing group, e.g. Contains carboxylate, sulfonate, sulfate, phosphate or phosphonate.

The foaming agents can be present in the toothpastes according to the invention in an amount of 0.1 to 6% by weight, based on the entire formulation.

(2) Phosphates as penetrants in the plaque film

The toothpastes according to the invention can contain, as an extremely preferred, optional component, 5 to 12% by weight, preferably 7 to 11% by weight, of a water-soluble phosphate as “penetrant” in the dental plaque film. Such soluble phosphoric acid salts serve to promote the penetration of fluoride ions through the naturally occurring saliva plaque film that forms on the teeth. Toothpastes containing fluoride and containing the amounts of phosphoric acid salts prescribed in this patent show an increased fluoride diffusion through the dental plaque and an improved absorption of fluoride through the tooth enamel in comparison with fluoride toothpastes which do not contain such phosphates as penetrants in the dental plaque film.

Although relatively high amounts of soluble phosphoric acid salts in fluorine-containing toothpastes can improve the ability of fluoride to penetrate the plaque film, the presence of such salts can reduce the stability of the soluble fluoride in such toothpastes during storage. However, it was surprisingly found that such soluble phosphates can be incorporated into the fluorine toothpastes containing silicon dioxide with particularly good fluoride compatibility, because the precipitated silicon dioxide abrasives treated with alkaline earth metal are used.

The phosphoric acid salts which may be present in the toothpastes according to the invention are water-soluble. For the purposes of the present invention, “water-soluble” phosphate is one that has a solubility of at least 3.0 g / 100 ml of H2O at 20 ° C.

The phosphates are compounds containing phosphorus, in the anions of which each phosphorus atom is surrounded by four oxygen atoms which are arranged at the corners of a tetrahedron. Common oxygen atoms in such tetrahedra can form chain, ring-shaped and branched polymers from interconnected P04 tetrahedra. Simple phosphates are the orthophosphates. The polymeric phosphates include the polyphosphates, e.g. Pyrophosphates and tripolyphosphates. Ring-shaped phosphates are the metaphosphates.

Examples of suitable water-soluble polyphosphates for the purpose according to the invention are tetrapotassium pyrophosphate, tetrasodium pyrophosphate, disodium pyrophosphate, sodium tripolyphosphate and potassium tripolyphosphate. Examples of suitable, water-soluble metaphosphates are monopotassium metaphosphate, sodium trimetaphosphate, sodium hexametaphosphate and sodium heptametaphosphate. Many of these water-soluble polyphosphates and metaphosphates are used in the form of hydrated salts.

The phosphates which are particularly preferred for the purpose according to the invention are the simple orthophosphoric acid salts. Orthophosphates are derived from the three-base orthophosphoric acid of the formula H3PO4. Water-soluble sodium, potassium and ammonium salts can be used.

There are approximately ten different crystalline sodium orthophosphates, including the different hydrates. Such salts are e.g. NaH2P04, NaH2P04-H20, NaH2P04-2H20, Na2HP04, Na2HP04-2H20,

Na2HP04 • 7H20, Na2HP04-12H20, Na3P04-6H20, Na3P04'8H20 and mixtures thereof. Preferred sodium orthophosphates are NaH2P04-H20, Na2HP04-2H20 and mixtures thereof. Mixtures of NaH2P04 * H20 and Na2HP04-2H20 in a weight ratio of approximately 1: 3 to 1: 5 are particularly preferred.

Potassium and ammonium orthophosphates can also be used as penetrants in the plaque film. Examples of such potassium and ammonium salts are: KH2P04, K2HP04, K2HP04-2H20, K2HP04-6H20, K3P04-3H20, K3P04-7H20, K3P04-9H20, (NH4) H2P04, (NH4) 2HP04i0 (NH4) and mixtures.

A phosphate mixture which is particularly preferred for use in the toothpastes according to the invention is a mixture of NaH2P04-H20 and K2HP04-2H20 in a weight ratio in the range from approximately 1: 3 to 1: 5.

The soluble phosphates used according to the invention are commercially available materials. Such phosphates suitable for the purposes of the invention are described in more detail in Kirk & Othmer, Encyclopedia of Chemical Technology, 2nd edition, volume 15, Interscience Publishers, Inc. (1968), pages 232 to 276.

The toothpastes according to the invention preferably result in phosphate concentrations of approximately 0.5 mol / 1000 g H20 to 2.0 mol / 1000 g H20 in the aqueous solutions which come into contact with the tooth surfaces when the toothpastes according to the invention are used in the mouth. In order to imitate such working solutions, the supernatant liquid of a centrifuged slurry of 1 part toothpaste in 3 parts water is used again.

If necessary, additional penetrants can also be added to the toothpaste film according to the fluorine-containing toothpastes according to the invention. Such optional components further increase the ability of fluoride to penetrate the plaque film obtained with the phosphates described above. Such means are, for example

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Hydroxy acids and salts thereof, e.g. Citric acid, trisodium citrate, malic acid and tartaric acid. If such additional penetrants are present in the dental plaque film, they can be used in an amount of 0.2 to 5.0% by weight, based on the toothpaste:

(3) Taste-improving or taste-correcting

medium

Suitable taste-correcting or taste-improving agents that can be added by toothpastes are wintergreen oil, peppermint oil, spearmint oil, sassafras oil and clove oil. Usable sweeteners are saccharin, dextrose, levulose, aspartame, D-tryptophan, acetosulpham, dihydrochalcone and sodium cyclamate. These taste-correcting or taste-improving agents are in the toothpastes according to the invention in general in amounts of 0.01 to 2% by weight and the sweeteners in general in amounts of 0.05 to approx. 3% by weight.

in front.

(4) Anti-plaque and anti-calculus agents

Phosphorus-containing agents against tartar formation and / or bis-biguanides as agents against plaque formation can also be optionally added to the toothpastes according to the invention. Anti-tartar agents containing phosphorus, e.g. Disodium ethane l-hydroxy-l, l-diphosph'onate and related materials are described in greater detail in McCune et al., U.S. Patent No. 3,488,419, issued January 6, 1970. Bis-biguanide anti-plaque agents such as e.g. Chlorhexidine, i.e. l.ö-bis-fN ^ p-chlorophenyl-N'-biguanidoj-hexane, and their soluble and insoluble salts and related materials, such as e.g. 1,2-bis (N5-p-trifluoromethylphenyl-N1-biguanido) ethane are described in more detail in U.S. Patent No. 3,934,002 to Haefele, issued January 20, 1976 in U.S. Patent No. 3,937,807 to Haefele, issued February 10, 1976, in Procter & Gamble BE-PS No. 843 244, published December 22, 1976, and in Procter & Gamble BE-PS No. 844 764 on January 31, 1977.

If optional anti-tartar agents and / or anti-plaque agents are present, they generally make up 0.01 to 2.5% by weight, based on the toothpastes described here.

(5) pigments and colorants, etc.

A large number of other optional components which are well known to the person skilled in the art can be added to the toothpastes according to the invention to improve the aesthetic properties. This includes pigments, dyes, speckling agents and the like. If these optional components are present, they generally make 0.001 to

2% by weight, based on the toothpastes.

The toothpastes according to the invention can be obtained by simply mixing the necessary and the optional components in any order and in a manner known per se. After production, these toothpastes have a pH of 4 to 8, preferably 6.5 to 7.5, provided that they are mixed with water in a weight ratio of

3 parts of water are slurried on 1 part of toothpaste. Fluoride toothpastes, which give pH values within a range from 4.0 to 8.0, have a particularly good effect against the solubility of the tooth enamel, compared to other toothpastes whose pH values are outside this range. To improve the taste of toothpastes within this pH range is also relatively easy.

The toothpastes according to the invention can be used in a conventional manner. Toothpastes or their slurries are known to be brushed onto the tooth surfaces and then washed away.

When the present toothpastes are used in a manner known per se, these pastes or slurries are generally in contact with the tooth surfaces for at least about 30 seconds. Such pastes 5 or slurries should preferably be in contact with the tooth surfaces for at least about 60 seconds.

The following examples illustrate the invention. In the following examples, parts mean parts by weight unless otherwise stated.

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Example 1 (comparative example)

In a 30,000 liter stainless steel reactor, which was provided with a jacket for steam heating, 1794 liters of sodium silicate solution (3.78% NaîO, 9.53% SÌO2) 15 with a specific weight of 1.121, containing 42 g NaîO per liter, registered. The reaction medium was then heated to 88 ° C. with constant stirring. At this point, 151.4 liters of a 10% sulfuric acid solution (specific gravity 1.066) and 351 liters of a sodium silicate-20 solution were simultaneously added to the reaction medium while maintaining the reaction temperature at 88 ° C ± 1 ° C. These two solutions were added over a predetermined time. After 47 minutes the silicate addition was stopped while the acid addition continued until the pH of the slurry was between 4.8 and 5.0. The reaction slurry was then boiled at 100 ° C for 20 minutes and the pH of the reaction mixture was readjusted to between 4.8 and 5.0. The resulting silica slurry was filtered and the residue washed to remove most of the by-product of the reaction (sodium sulfate). The filter cake was then dried and the dried product was ground to the desired fineness.

The dry silicon dioxide thus obtained was subjected to various physico-chemical tests. The corresponding analytical values can be found in Table I below. This example represents a comparative test in which no alkaline earth metal is added.

40 Example 2

A 30,000 liter stainless steel reactor equipped with a jacket for steam heating was filled with 1,794 liters of sodium silicate solution (3.78% NajO and 9.53% SÌO2) with a specific gravity of 1.121, containing 42 g 45 Na20 per liter , loaded. Then the reaction mixture was heated to 88 ° C. with constant stirring. At this point, 151.4 liters of a 10% sulfuric acid solution (specific gravity 1.066) and 351 liters of a sodium silicate solution were simultaneously added to the reaction medium while maintaining the reaction temperature at 88 ° C ± 1 ° C. These two solutions were added over a predetermined time. After 47 minutes, the silicate addition was stopped while the acid addition continued until the pH of the slurry was between 4.8 and 5.0. The reaction slurry was then boiled at 100 ° C for 20 minutes and the pH of the reaction mixture was readjusted to between 4.8 and 5. The silica slurry thus obtained was filtered and the residue was washed to remove most of the sodium sulfate as a by-product of the reaction.

The washed filter cake was then reslurried by stirring at ambient temperature without adding water. With stirring, the slurry was treated with 102 g of 65 hydrated lime (calcium hydroxide) of the so-called Codex purity grade (a purity grade that applies to food in the United States) to recover 25 ppm calcium ions based on the total weight of dry

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barely solid product in the slurry. After treatment with the calcium ions, the slurry of the filter cake was stirred vigorously for 15 minutes to achieve the effective amount of calcium ions on the surface of the silica abrasive. The product so obtained was then spray dried and milled at an inlet temperature of 483 ° C and an outlet temperature of 122 ° C. Its abrasive and physical properties were determined in the same manner as for the abrasive of Example 1.

Example 3

The procedure was the same as in Example 2, with the difference that the sulfuric acid was added at a rate of 162.7 liters per minute, while 204 g of calcium hydroxide were added, so that 50 ppm of calcium ions resulted. The product was then also characterized.

increased to 170.3 liters / minute, but the rate of silicate addition remained at 315.7 liters / minute.

The washed filter cake was treated with 816 g calcium hydroxide to give 200 ppm calcium ion on 5 the surface of the silica abrasive. The product was then characterized.

Example 7

The procedure is the same as in Example 2, with the difference that the calcium ions are added in the form of 2040 g of calcium hydroxide, 500 ppm of calcium ions being obtained. The product was then characterized.

As already indicated, the products obtained according to Examples 1 to 7 were examined with regard to their physical properties. The results can be found in Table I below.

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Example 4 20

This example corresponded to Example 2 with the difference that the sulfuric acid was added at a rate of 166.5 liters per minute and 408 g calcium hydroxide were added so that 100 ppm calcium ions resulted in the silica. The product was then also characterized.

Example 5

In this example, a silicon dioxide abrasive for dentifrices was prepared by first filling the reactor with 1.420 liters of sodium silicate solution (4.09% Na21 and 10.31% SÌO2) with a specific weight of 1.131, containing 46.3 g Na2Ü per liter, as the reaction medium. The reactor was then heated to 91 ° C. with constant stirring. At this point, 162.7 liters of a 12% sulfuric acid solution (specific gravity 1.08) and 315.7 liters of a sodium silicate solution were simultaneously added to the reaction medium per minute while maintaining the reaction temperature at 91 ° C ± 1 ° C. The silicate addition was stopped after 47 minutes, but the acid addition continued until the pH of the slurry was between 4.6 and 4.8. The reaction slurry was then boiled at 100 ° C for 20 minutes and the pH of the reaction product was readjusted to between 4.6 and 4.8. The resulting silica slurry was filtered and the residue washed to remove the sodium sulfate by-product.

The washed filter cake was then reslurried by stirring at ambient temperature without adding water. With stirring, the slurry was then treated with 510 grams of Codex (US Food Grade) hydrated lime (calcium hydroxide) to introduce 125 ppm calcium ions based on the total weight of the dry, recoverable silica abrasive contained in the slurry. After this treatment with the calcium ions, the slurry of the filter cake was stirred vigorously for 15 minutes to achieve an effective amount of calcium ions on the surfaces of the silica abrasive. The product so obtained was then spray dried at an inlet temperature of 483 ° C and an outlet temperature of 122 ° C, ground and then characterized.

TABLE I

example

% LOI *

Pack

Oil-free

BET upper

By

No.

dense sorp flat

sleek

(g / ml)

tion **

che ***

particle

(ml /

(m2 / g)

size****

100 g)

(around)

1

5.0

0.35

94

151

7.7

2nd

4.4

0.43

89

234

8.6

3rd

5.5

0.40

90

227

7.8

4th

4.9

0.41

91

192

7.9

5

6.0

0.47

85

215

11.0

6

5.4

0.50

78

201

14.5

7

5.1

0.32

95

172

7.6

* Water loss when heating pre-dried silicon dioxide abrasive from 105 ° C to 900 ° C ** Determination of oil absorption: ASTM, D281-31 *** J. Am. Chem. Soc. 60, 309-319 (1938)

**** Measured with Coulter Counter Model TA II

Various toothpastes according to the invention are given in the following examples, the precipitated silicon dioxide abrasives obtained according to the invention being used in each case.

Example 8

A toothpaste was formulated using the precipitated silicon dioxide abrasive according to Example 2; it had the following composition:

50

Example 6

This example was carried out in the same way as Example 5, with the difference that the reactor was first charged with 1,608 liters of sodium silicate solution as the reaction medium and the rate of acid addition

65

component

Precipitated silica abrasive (example 2)

Sodium fluoride (NaF)

Sorbitol solution (70%)

Glycerin

Sodium carrageenan

Monosodium orthophosphate monohydrate (NaH2P04-H20)

Disodium orthophosphate dihydrate (Na2HP04-2H20)

Sodium alkyl sulfate solution (28.8%) coconut monoglyceride sodium sulfonate flavor-enhancing agent sodium saccharin

Dye (FD&G Blue No. 1 solution, 1%)

Titanium dioxide (TÌO2)

Trisodium citrate dihydrate

(C6H5Na307-2H20)

Distilled water

total

Quantity (% by weight)

16.0 0.28 32.0 13.0 0.75

2.15

8.34

6.0

0.9

1.22

0.3

0.35

0.5

0.25 balance 100.0

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The above-mentioned toothpaste was prepared by mixing the components mentioned in a manner normal for the production of toothpaste. The water component was preferably first placed in a suitable container, after which the penetrants into the plaque film, the flavor-enhancing component (s), the humectant and then the other components were added in succession with moderate stirring.

A slurry obtained from the above freshly prepared toothpaste with water (mixing ratio water to toothpaste 3: 1) gave a pH of approximately 7.1.

Thanks to the high toothpaste fluoride compatibility, such a toothpaste was used to achieve an inexpensive fluoride treatment for toothbrushes brushed with it. The toothpaste also had a good cleaning effect and an RDA value of 100. If such a toothpaste was stored for an extended period at approx. 27 ° C., a minimal loss of soluble fluoride was found.

Toothpastes that achieved substantially similar benefits in fluoride treatment, similar toothpaste fluoride tolerances, and similar cleaning performance could be made by replacing sodium fluoride in the toothpaste of Example 8 with an equivalent amount of stannofluoride, sodium chlorofluoride, potassium fluoride, a mixture of potassium fluoride and replaced stannofluoride, indium fluoride, zinc fluoride or ammonium fluoride.

Toothpastes that achieved substantially similar benefits in fluoride treatment and substantially similar cleaning performance were obtained when, in the toothpaste of Example 8, the phosphoric acid salt mixture was replaced by an equivalent amount of NaH2P04, NaH2P04-H20,

NaH2P04-2H20, Na2HP04, Na2HP04-2H20,

Na2HP04-7H20, Na3P04-6H20, Na3P04-8H20, KH2P04, K2HP04, K2HP04-2H20, K2HP04-6H20, K3P04-3H20, K3P04-7H20, K3P04-4H4, NH3 (NH) or other mixtures of NaH2P04-H20 and Na2HP0j-2H20 with a weight ratio of monosodium to disodium compound of approx. 1: 3 to 1: 5 or of mixtures of NaH2P04-H20 and K2HP04-2H20 with a weight ratio of sodium to potassium salt of approx 1: 3 to 1: 5, tetrapotassium pyrophosphate, tetrasodium pyrophosphate, disodium pyrophosphate, sodium tripolyphosphate, potassium tripolyphosphate, monopotassium metaphosphate, sodium trimetaphosphate, sodium hexametaphosphate or sodium heptametaphosphate ratio of 3: if 1 replaced a toothpaste value of 4, if this replaced a toothpaste 3 value, if 1 replaced a toothpaste value of 4, if this replaced a tooth value of 4 in 1 , Had 0 to 8.0.

Example 9

A high abrasive toothpaste was obtained using the precipitated silica abrasive of Example 3; it had the following composition:

Component quantity

(Wt. 9b)

Precipitated silica abrasive

(Example 3) 35.0

Sodium fluoride (NaF) 0.22

Glycerin 5.0

Sorbitol solution (70%) 20.0

Carboxymethyl cellulose (degree of substitution 0.7) 0.5

Magnesium aluminum silicate (Veegum flakes) 0.3 monosodium orthophosphate monohydrate

(NaH2P04-H20) 0.3 disodium orthophosphate dihydrate

(Na2HP04 ■ 2H20) 0.3

Sodium alkyl sulfate solution (28.8 yen) 2.3

Coconut monoglyceride sodium sulfonate 0.7

Taste-improving agent 0.9

Sodium saccharin 0.2

Titanium dioxide (Ti02) 0.5

Sprinkling agent 0.5

Distilled water rest

Total 100.0

Toothpastes with essentially similar advantageous fluoride treatment properties, similar toothpaste-fluoride compatibility and similar cleaning performance were obtained if, in the toothpaste of Example 9, the precipitated silicon dioxide abrasive prepared according to Example 3 was replaced by an equivalent amount of the abrasives according to Examples 2, 4, 5 and 6 were replaced.

Toothpastes that had substantially similar benefits of fluoride treatment and substantially similar cleaning performance could be made if, in the toothpaste of Example 9, the phosphoric acid salt mixture was replaced by an equivalent amount of NaH2P04, NaH2P04-H20, NaH2P04-2H20, Na2HP04, Na2HP04-2H20,

Na2HP04 ■ 7H20, Na3P04-6H20, Na3P04-8H20, KH2P04, K2HP04, K2HP04-2H20, K2HP04 • 6H20, K3P04-3H20, K3P04-7H20, K3P04-4H4, NH3 (NH) or other mixtures of NaH2P04-H20 and Na2HP04 • 2H20 with a weight ratio of monosodium compound to disodium compound of approx. 1: 3 to 1: 5, of mixtures of NaH2P04-H20 and K2HP04-2H20 with a weight ratio of sodium to potassium salt of approx. 1: 3 to 1: 5, tetrapotassium pyrophosphate, tetrasodium pyrophosphate, disodium pyrophosphate, sodium tripolyphosphate, potassium tripolyphosphate, monopotassium metaphosphate, sodium trimetaphosphate, sodium hexametaphosphate or sodium heptametaphosphate replaced the toothpaste with a toothpaste that replaced 3 with toothpaste with a toothpaste that replaced tooth with toothpaste, if toothpaste replaced 3 tooth 1 had a pH of 4.0 to 8.0.

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Example 10

A clear toothpaste was formulated using the precipitated silica abrasive from Example 4; it had the following composition:

Component quantity

(% By weight)

Precipitated silica abrasive

(Example 4) 20.0

Sodium fluoride (NaF) 0.24

Sorbitol solution (70%) 57.0

Glycerin 15.0

Sodium carrageenan. 0.5

Phosphoric acid (85%) 0.10

Sodium alkyl sulfate solution (28.8%) 4.0

Taste-improving agent 1.0

Sodium saccharin 0.2

Dye (FD&C Blue No. 1 solution, 1%) 0.05

Distilled water rest

Total 100.0

Example 11

A low abrasive toothpaste was formulated using the precipitated silica abrasive of Example 3; it had the following composition:

component

amount

(% By weight)

Precipitated silica abrasive

(Example 3)

6.0

Stannofluoride (SnF2)

0.40

Sorbitol solution (70%)

51.0

Glycerin

25.6

Sodium carboxymethyl cellulose

(Degree of substitution 0.7)

1.0

Sorbitan monoisostearate

2.00

Sodium alkyl sulfate solution (28.8%)

6.0

Taste-improving agent

1.20

Sodium saccharin

0.28

Dye (FD&C Blue No. 1 solution, 1%)

0.25

Fumed colloidal silica

(Aerosil 200V) *

5.00

Distilled water

rest

total

100.0

* distributed by Degussa, Inc.

Toothpastes with substantially similar fluoride treatment benefits, toothpaste fluoride compatibility, and cleaning performance were obtained when, in the toothpaste of Example 10, the precipitated silica abrasive prepared according to Example 4 was obtained by an equivalent amount of that of Examples 2, 3, 5 and 6 Abrasive was replaced.

A toothpaste with essentially similar advantages in the fluoride treatment and with an improved anti-tartar effect was obtained if the toothpaste according to Example 10 was additionally added with about 1.0% by weight disodium ethane-1-hydroxy-l, 1-diphosphonate .

Test and assessment procedures

The present precipitated silica abrasives can be used to make particularly advantageous therapeutic toothpastes containing soluble phosphates as penetrants in the plaque film. Such toothpastes have a high abrasive fluoride compatibility as well as an excellent tooth cleaning performance. The following tests and evaluations serve to demonstrate the excellent fluoride compatibility which is achieved with the precipitated silicon dioxide abrasives according to the invention for dental purposes in the toothpastes according to the invention. It is also shown below that the abrasives according to the invention have a higher abrasive fluoride compatibility than abrasives produced in a similar manner, but which have not been treated so that they contain substantial amounts of an alkaline earth material. The excellent cleaning performance of the toothpastes according to the invention is also proven. Finally, it is shown that abrasives manufactured using the so-called sulphate lye process - even if they contain alkaline earth materials - do not have the same fluoride tolerance values as the present precipitated silicon dioxide abrasives manufactured using the fresh water process.

Abrasive fluoride compatibility

Precipitated silica abrasives for dental use can be tested for relative compatibility with fluoride materials using a 24 hour abrasive slurry test. Such a test can be used to obtain values which allow predictions of the availability of soluble fluoride in certain types of fluoride-containing toothpastes after storage at approximately 27 ° C. for approximately four weeks.

The 24 hour abrasive slurry test is used to obtain fluoride tolerance values; these are defined as the percentage of the theoretically maximum accessible fluoride that is actually determined as soluble fluoride after 24 hours using the following test method. In this method (Orion Specific Ion Electrode Method), a standard sodium fluoride stock solution containing 1624 ppm fluoride is prepared by deionizing 2.80 g sodium fluoride, 21.5 g NaH2P04 and 83.4 g Na2HP04-2H20 in 672.5 g distilled water dissolves and stored in a polyethylene bottle. Weigh 30 g of this solution. 7 g of the silica abrasive to be tested is then dispersed in the solution and left in contact with it for 24 hours at a temperature of about 37.8 ° C (100 ° F). After 24 hours, the precipitated silica abrasive and fluoride-containing solution is centrifuged at 15,000 rpm for 20 minutes or until the supernatant is clear. 10 ml of the supernatant liquid are then pipetted into a plastic ampoule. Then 10 ml EDTA / THAM solution are also pipetted into the plastic ampoule. The EDTA / THAM solution is 0.2 molar in EDTA (disodium salt of ethylenediaminetetraacetic acid) and 0.2 molar in THAM (2 - amino-2-hydroxymethyl-1,2-propanediol), and its pH is with sodium hydroxide set to 8.0. A magnetic stir bar is added, followed by gentle stirring. The fluoride ion concentration is determined by direct potentiometry with an Orion fluoride electrode (model 95-09). The EMF is converted into ppm fluoride in the supernatant liquid using a logarithmic equation. The fluoride compatibility value is then calculated by expressing the measured ppm of soluble fluoride as a percentage of the theoretically available soluble fluoride.

Using this method, the relative abrasive fluoride compatibility values for the various abrasives obtained in Examples 1-7 are determined. The results of these evaluations can be found in Table II below.

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TABLE II

12

TABLE III

Abrasive Fluoride Compatibility Example No. Calcium Abrasive Fluoride Compatibility

treatment sensibility

(ppm)

1 (comparison)

0

76%

2nd

25th

93%

3rd

50

94%

4th

100

93%

5

125

91%

6

200

90%

7

500

88%

From Table II it can be seen that the precipitated silicon dioxide abrasives according to the invention, which contain certain amounts of alkaline earth metals, have considerably better abrasive fluoride compatibility values than an abrasive free from alkaline earth metal, which is otherwise produced in the same way. Thus, the precipitated silica abrasives obtained according to Examples 2 to 6 should be suitable for the production of toothpastes which contain fluoride ions and penetrants in the dental plaque film and which have a high abrasive fluoride compatibility.

Compatibility with fluoride in toothpastes

The present preferred toothpastes containing precipitated silica abrasives and plaque film penetrants were evaluated for their abrasive fluoride compatibility. The toothpastes produced for evaluation had the composition of Example 8 and differed only in the abrasive component.

To determine the fluoride tolerance values for the toothpastes tested, a similar determination method for soluble fluoride was used as that described above for the determination of the abrasive fluoride tolerance. According to this method, the toothpastes were kept in a laminated tube for a certain time. 15.0 g of the toothpaste were then poured into a 100 ml beaker and 45.0 g of distilled water were then added. The mixture was then stirred to form a slurry in which the toothpaste was evenly dispersed. The slurry was then centrifuged at 15,000 rpm for 20 minutes or until the supernatant was clear.

The supernatant was then treated as in the abrasive fluoride compatibility determination method described above. The concentration of soluble fluoride was determined in a similar manner and an abrasive fluoride compatibility value was calculated for each toothpaste in a similar manner. The toothpaste fluoride compatibility values of the relevant toothpastes evaluated can be found in Table III. The abrasives evaluated are the abrasives obtained as described in Examples 1-7, which are characterized in Table I above.

Toothpaste Fluoride Compatibility Abrasive Calcium Toothpaste Fluoride Compatibility

(Example No.) treatment ability

(ppm) (after 1 week at 27 ° C)

1 (comparison)

0

76%

2nd

25th

99%

3rd

50

98%

4th

100

99%

5

125

97%

6

200

94%

7

500

90%

The values given in Table III clearly show that the preferred toothpastes according to the invention, which contain the present precipitated silicon dioxide abrasives, have better abrasive fluoride tolerance than a similar toothpaste, but which does not contain the precipitated precipitated alkaline earth metal prepared by the method of Example 1 Contained silica abrasives. The values in Table III also show that the accessibility of soluble fluoride from the fluoride ion source did not decrease significantly when stored using the silica abrasives of the invention in the preferred toothpastes of this invention.

It should be noted, however, that the amount of accessible soluble fluoride decreases to a certain extent even in the toothpastes according to the invention with increasing duration and temperature of storage. For example, toothpaste fluoride compatibility values for toothpastes stored for extended periods of time or at higher temperatures are generally lower than those mentioned above.

Additional abrasive fluoride compatibility values for various toothpastes that show the influence of longer storage or storage at higher temperatures can be found in Table IV.

TABLE IV

Toothpaste fluoride compatibility (high temperature, extended storage)

Abrasive calcium toothpaste fluoride compatibility medium treatment 1 week 1 week 4 months 5 months (example (ppm) approx. 27 ° C approx. 49 ° C approx. 27 ° C approx. 27 ° C No.)

1

0

76%

64%

64%

2nd

25th

99%

97%

91%

-

3rd

50

98%

96%

91%

-

4th

100

99%

95%

91%

-

5

125

97%

92%

-

-

6

200

94%

90%

-

-

7

500

90%

86%

-

89%

The data shown in Table IV show that the preferred toothpastes according to the invention retain relatively high abrasive fluoride compatibility values even when stored for a long time or under harsh storage conditions.

Cleaning performance

The tooth cleaning ability of the silica abrasives described here can be estimated using the Radioactive Dentin Abrasion Test (RDA) method. The RDA values can be used to determine the relative cleaning performance of various abrasives for any type

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dentifrice abrasives. For precipitated silicon dioxide abrasives, an RDA value (measured according to the method given below) of at least 40, preferably between 70 and 120, is required in order to ensure a sufficiently good grinding effect for an effective cleaning dentifrice. The prior art precipitated silica abrasives, which have high toothpaste fluoride compatibility, are generally poor oral hygiene cleaners, as evidenced by their low RDA values. However, the abrasives treated with alkaline earth have both a good tooth cleaning effect and a high fluoride tolerance.

Several commercially available precipitated silicon dioxide abrasives, which have a relatively high toothpaste fluoride compatibility according to the present determination method, were consulted for the evaluation of the RDA values. The test was carried out using a conventional toothpaste base with the same composition as in Example 8, only the abrasive component being changed.

The method used to determine the RDA values for toothpastes summarized in Table V is described below. This test method is described in more detail in the Journal of Dental Research, July-August 1976, by Hefferren, pp. 563-573. The specific levels for determining RDA values are as follows:

A. Selection and preparation of the teeth

Healthy teeth with simple roots that were caries-free and viable when extracted were selected.

Then they were scraped in with a scalpel. The crown and root tip of each tooth were removed using a grinding wheel to produce a 14 mm long and at least 2 mm wide dentin sample at the narrower end. Cut pieces of the root (dentin chips) or alternatively another tooth were also prepared for later use in determining a correction factor for the self-absorption of radiation.

B. Radiation of the dentin

The prepared roots and dentin chips described in stage A were exposed to a neutron flux of 2 x 1012 neutrons / cm2 for 3 hours.

C. Assembling the roots

After the irradiation had taken place, the irradiated roots were embedded in a holder made of cold-curing dental methacrylic resin and mounted on a cross-brushing machine. The toothbrushes used during this test were medium-hard, flat 50-tufted "pepsodent" toothbrushes.

D. Preconditioning of the dentin surfaces

Before the start of the first test, the freshly assembled, irradiated roots were brushed with a standard slurry (10 g calcium pyrophosphate + 50 ml of a solution containing 0.5% carboxymethyl cellulose and 10% glycerol) with 6,000 brush strokes. At the start of each test that took place the following day, the roots were brushed with 100,000 strokes.

E. Actual test

After preconditioning, the dentin samples were then conditioned with the standard slurry (same slurry as in Step D) at the beginning, during and at the end of each test with 1,500 brushstrokes. The actual test consisted of brushing the dentin samples with 1,500 brush strokes using a slurry of the test product (25 g dentifrice + 40 ml deionized distilled water).

F. Preparation of the correction factors

The correction factors were prepared by dissolving the dentin chips or alternatively another tooth from stage B in 5 ml of concentrated hydrochloric acid, which was made up to a volume of 250 ml with distilled water. 1 ml of this solution was added to test pastes and standard slurries prepared in a manner similar to Step E and then neutralized with 0.1 normal NaOH.

Measurement of radioactivity

The radioactivity of the slurry samples (1.0 ml) was determined using an "Intertechnique SL-30" liquid scintillation counter. Alternative counting method: 3 ml aliquots of each slurry were transferred to flat-bottomed stainless steel disks measuring 25 mm x 8 mm and counted using a "Nuclear Chicago" Geiger counter.

Calculations

The radioactive dentin abrasion values (RDA) for a particular paste correspond to the ratio of the average corrected count for the paste in question and the average count for the standard slurry, multiplied by 100. The reference abrasive became an arbitrary dentin abrasion value of 100 units allocated.

The results of these RDA value determinations can be found in the following Table V.

TABLE V

Radioactive dentin abrasion values abrasives RDA toothpaste fluoride

inertia after 1 week (approx. 27 ° C)

A. (Example No.)

1 (comparison) 75 ± 7 76%

2 80 ± 21 99%

3 67 + 8 98%

4 80 ± 1 99%

5 103 ± 5 97%

6 111 ± 5 94%

7 56 ± 4 90%

B. Commercially available precipitated silica products

8 Sident 3L 14 + 2 92%

9 Neosyl2- 25 + 2 78%

10 QUSO G-303- 22 ± 2 87%

11 Neosyl ET4- 26 + 4 84%

'• A precipitated silica sold by Degussa, Inc. (N.Y.C., USA).

2- One from Joseph Crosfield & Sons, Ltd. (London, UK) precipitated silica sold.

3- A precipitated silica sold by Philadelphia Quartz Co. (Valley Forge, PA, USA).

4- One from Joseph Crosfield & Sons, Ltd. expelled precipitated silica.

The values in Table V show that the commercially available precipitated silicon dioxide abrasives may have a high compatibility with abrasive fluoride, but do not have sufficient abrasive properties to be useful as an abrasive for dentifrices. Surprisingly, the new precipitated silicon dioxide abrasives according to the invention show excellent abrasive fluoride compatibility and at the same time give excellent RDA grinding effects.

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14

values that can be used as an indicator of relative tooth cleaning performance.

Comparison of «fresh water» and «sulphate lye» abrasives

As has already been explained above, the abrasive products according to the invention are related to but significantly different from the calcium-treated silicas of the US patent application Ser. No. 826 901. To prove this difference, the following evaluation was made to determine the fluoride compatibility of the products of U.S. Patent Application Ser. No. 826 901 to be compared with the fluoride compatibility of the abrasive products according to the invention. The tested “sulphate lye” silicon dioxide materials were tested according to the method described in the US patent application Ser. No. 826 901 and processes described in U.S. Patent No. 3,960,586, issued June 1, 1976, are prepared as follows:

Dry sodium sulfate was added to 37.854 liters of water in a 757 liter reactor so that the sodium sulfate concentration in the reaction medium was 10%. The pH of the reaction medium was then adjusted to 9.0 by adding 20% sodium silicate. The reaction temperature was 65 ° C (150 ° F). The sodium silicate solution had a molar ratio of Si02 / Na20 of 2.5 and a concentration of 0.240 kg / liter. The sodium silicate was added to the reaction medium within 4 minutes. At this point 25 the addition of sodium silicate was interrupted, whereupon 11.4% sulfuric acid was added to the reaction medium until a pH of 9.0 was reached. At this point, the sodium silicate solution and the sulfuric acid solution were added simultaneously for 35 minutes. After the lapse of 30 minutes, the silicate addition was stopped and the acid addition continued until a slurry with a pH of 5.5 was obtained. The mixture was digested at 77 ° C for 20 minutes and the wet filter cake thus obtained was collected and washed. 35

The moist filter cake was then treated in the same manner as in Example 2, divided into six separate portions and treated with 50, 100, 200, 400 and 800 ppm calcium from aqueous calcium hydroxide solutions. Each moist filter cake was then dried and treated and characterized as in Example 2. The values obtained can be found in the following Table VI, in which the first abrasive represents a comparison test in which no calcium was added.

TABLE VI

«Sulphate lye» - Calcium addition of abrasive

Abrasive (ppm) fluoride compatibility *

A 0 (comparison) 88

B 50 89

C 100 88

D 200 88

E 400 86

F 800 82

* Determined using the method described for Table II.

As can be seen from the data given in Table VI, the calcium-treated "sulfate lye" abrasives of US patent application Ser. No. 826 901 abrasive fluoride compatibility values that are generally lower than those of the "fresh water" silicon dioxide abrasives according to the invention (see Table II). Furthermore, it can be seen that the addition of an alkaline earth metal to abrasives produced according to the "sulfate lye" method does not result in a surprising improvement in the abrasive fluoride compatibility. On the other hand, as a comparison with Table II shows, the addition of equivalent amounts of an alkaline earth metal to the silicon dioxide abrasives of this invention made by the "fresh water" method results in a very surprising improvement in abrasive fluoride compatibility.

v

Claims (19)

640 135 2nd PATENT CLAIMS 1. Abrasive, characterized in that it contains a precipitated, amorphous silicon dioxide which contains 10 to 300 parts of alkaline earth metal ions per million parts of amorphous silicon dioxide and which also has a radioactive dentin abrasion value of at least 40, a packing density of 0.24 to 0, 55 g / ml, an oil absorption of 70 to 95 ml / 100 g, a BET surface area of 100 to 250 m2 / g, a percentage loss on ignition of 4 to 6% and fluoride compatibility values of at least 90% if it is incorporated into fluoride-containing toothpastes , having. 2. Abrasive according to claim 1, characterized in that the alkaline earth metal ions are calcium, strontium or magnesium ions. 3. Abrasive according to claim 1, characterized in that the amount of alkaline earth metal ions is 10 to 100 parts per million parts. 4. Abrasive according to claim 1, characterized in that the alkaline earth metal ions are calcium ions. 5. A process for producing an abrasive according to claim 1, characterized in that an alkali metal silicate with a molar ratio of SÌO2 to X2O of 2.0 to 2.7, wherein X is an alkali metal, is dissolved in water and the solution at a Acidify the reaction temperature in the range of 77 to 91 ° C with a mineral acid until the precipitation of the silica is substantially complete, thereafter continue the mineral acid addition until the pH is 6.0 or less, then the material obtained at a temperature , which is 10 to 30 ° C higher than the reaction temperature, digested for 10 to 30 minutes, the slurry thus obtained is filtered and the solid product is washed with fresh water, the resulting wet filter cake is reslurried in water with stirring and so much alkaline earth metal ions in Form of a sufficiently soluble alkaline earth metal salt adds that the wet filter cake alkaline earth metal ions in an amount of 10 to 300 parts per million parts, based on the dry, recoverable product in the slurry, the mixture thus obtained is stirred to ensure that the effective amount of the alkaline earth metal ions adhere to the surface of the silica, and finally the solid product dries and wins. 6. The method according to claim 5, characterized in that the mineral acid used is sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid and / or carbonic acid. 7. The method according to claim 6, characterized in that initially only part of the alkali metal silicate is acidified with the mineral acid and then the remaining part of the alkali metal silicate solution is added simultaneously with the mineral acid. 8. The method according to claim 6, characterized in that the alkaline earth metal ions are ions of calcium, strontium and / or magnesium. 9. The method according to claim 6, characterized in that the alkaline earth metal ions are calcium ions and are added in the form of calcium hydroxide, calcium oxide, calcium nitrate and / or calcium fluoride. 10. The method according to claim 6, characterized in that the slurry of the moist filter cake is brought into contact with the alkaline earth metal ions at room temperature. 11. The method according to claim 10, characterized in that drying the alkaline earth metal-treated silicon dioxide by spray drying. 12. The method according to claim 6, characterized in that sodium silicate is used as the alkali metal silicate, sulfuric acid is used as the acidifying acid, the alkaline earth metal ions are added in the form of calcium hydroxide and the process is such that 10 to 100 parts of calcium ions are used per Brings millions of parts into intimate contact with the silicon dioxide product. 13. Toothpaste, characterized in that it (A) 6 to 35% by weight of a precipitated silicon dioxide abrasive according to claim 1, (B) 0.01 to 3.0% by weight of a water-soluble, fluorine-containing material which forms fluoride ions in aqueous solution, (C) 3 to 55% by weight of a humectant, (D) 0.2 to 2.0% by weight of a binder and (E) contains 15 to 80% by weight <% of water and has a pH of 4 to 8 when slurried with water in a weight ratio of 3 parts by weight of water to 1 part by weight of toothpaste. 14. Toothpaste according to claim 13, characterized in that it additionally 5 to 12 wt .-% of a water-soluble phosphate as a penetrant in the dental plaque film, which is selected from salts of orthophosphoric acid, pyrophosphoric acid, tri-polyphosphoric acid and metaphosphoric acid, contains. 15. Toothpaste according to claim 14, characterized in that (A) the precipitated silica abrasive makes up 10 to 20% by weight of toothpaste, (B) the fluorine-containing material is 0.1 to 1.0% by weight of the toothpaste, (C) the humectant makes up 20 to 35% by weight of the toothpaste, (D) the water content is 15 to 40% by weight and (E) the pH of a slurry of 1 part by weight of toothpaste in 3 parts by weight of water is 6.5 to 7.5. 16. Toothpaste according to claim 15, characterized in that it additionally contains 0.1 to 6 wt .-% of a foaming agent, wherein (A) the fluorine-containing material is sodium fluoride and / or stannofluoride, (B) the phosphate is an orthophosphate and (C) the humectant is glycerin, sorbitol, xylitol, or a mixture thereof. 17. Toothpaste according to claim 16, characterized in that (A) the fluorine-containing material is sodium fluoride, (B) the foaming agent 1) water-soluble salts of alkyl sulfuric acids with 8 to 18 carbon atoms in the alkyl radical, 2) water-soluble salts of sulfonated monoglycerides of fatty acids with 8 to 18 carbon atoms in the fatty acid residue and 3) Mixtures of which is selected. 18. Toothpaste according to claim 15, characterized in that carragheen is used as a binder. 19. Toothpaste according to claim 16, characterized in that it also contains 0.2 to 5 wt .-% of another penetrant in the plaque film, which is selected from citric acid, trisodium citrate, malic acid and tartaric acid, wherein (A) the fluorine-containing material is sodium fluoride and (B) the phosphate is a mixture of sodium dihydrogenphosphate monohydrate and disodium hydrogenphosphate dihydrate in a weight ratio of monosodium salt to disodium salt of 1: 3 to 1: 5. 20. Toothpaste according to claim 15, characterized in that it contains an additional component which (A) 0.01 to 2% by weight of a taste-improving or taste-imparting agent, (B) 0.05 to 3% by weight of a sweetener, 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65 3rd 640 135 (C) 0.01 to 2.5% by weight disodium-ethane-1-hydroxy-1,1-diphosphonate as an agent against tartar formation, (D) 0.01 to 2.5% by weight of a bis-biguanide anti-plaque agent and (E) mixtures of these additional components is selected.